The field [math]\phi affects evolution of matter density perturbation and perturbation of expansion rate [math]\mathcal{Z} and [math]m=\infty corresponds to GR. The lower value contributes to ISW effect and increase low [math]l value of [math]C_l. (it's similar to normal quintessence but it does not affects background evolution.)

The problem is when I increase the value of [math]m the computation of CAMB slows a lot. (for low value like [math]m=1 it only takes less than 2 seconds but for [math]m > 10^4 it takes more than 10 minutes.) I added the new field as the same way for quintessence. There is no error in output values.
How can I speed up the code to use CosmoMC in my personal computer? Or is there any fast approximation scheme for solving KG equation?

I use CAMB files in CosmoMC master branch(downloaded at 19/07/01) and my CPU is AMD ryzen 7 2700X (8 core).